This invention relates to a pneumatic tire which reduces non-uniform wear of a tire tread surface and noise at the time of running, and more particularly to a pneumatic tire for a passenger car.
In tires in general which have a tread pattern consisting of blocks on a tire tread surface (or those tires which have so-called "block-based pattern"), if the angle between two adjacent sides of a block tread surface forming the edge of the block is an acute angle when viewed on a plane, the edge portion has lower rigidity than other portions inside the block so that a contact pressure at the time of running is lower than that of other portions inside the block. Accordingly, wear is more greatly retarded at this edge portion than at other portions and non-uniform wear thus takes place on the block tread surface. Since this edge portion has lower rigidity than other portions inside the block, the edge portion vibrates during running and a high frequency noise is generated from this edge portion.
In order to cope with the problem described above, it has been a customary practice to make chamfering in such a manner as to cut obliquely the edge portion of the block (e.g. Japanese Patent Laid-Open No. 181904/1987). According to this structure, however, an angular ridge occurs at the boundary between the block tread surface and the chamfer surface and hence, it is difficult to sufficiently suppress the occurrence of non-uniform wear and the high frequency noise. If chamfering is drastically made, the appearance of the tread pattern is deteriorated.